uploading a powerpoint presentation in knowledgemanagement

Can any one please tell the procedure how to upload a power point presentation which is present on my desktop to knowledge management folder.....

Let me explain you in detail

I will logon to portal then I will click on one of the role.Lets say it as some xyz role

Once i click on that xyz role...to the left hand side i will get some options related to that role....once i click on that option a blank table format gets displayed on the right hand side..column ...In that table i need to upload the power point documents